1. Field of the Invention
This invention relates to powder coating systems. More particularly this invention relates to a powder coating booth in which air is recirculated in a controlled fashion to enhance transfer efficiency to the articles being coated, to improve over spray coating particle recovery and to protect the spray gun operator from coating particles.
2. State of the Art
In wet paint spray booths, water curtains are often used to entrap over spray paint particles with no attempt being made to recover the paint particles. With powder coating systems, the expense of the paint coating particles requires recovery of as much as possible of the overspray particles, that is, the particles not adhering to the product being coated.
Typically in powder coating systems, the operator introduces his electrostatic spray gun through an open window in the spray booth to spray the coating particles against the articles being coated. Air is drawn into the booth through the window by an exhaust fan to entrain the overspray particles. The particle laden air is drawn out of the bottom of the booth and passed through a filter to remove the coating particles with the clean air being exhausted back to the shop environment from which the air was drawn.
When articles being sprayed are conveyed through the powder coating booth, air will also be drawn into the end wall openings through which the articles being coated pass. Also some air will pass into the booth through the conveyer opening in the top of the booth.
In these prior art structures, there is no attempt made to direct the air in a particular manner past the articles being sprayed so as to optimize transfer efficiency and particle recovery. Also there is no attempt made to isolate the spray gun operator to eliminate or minimize back spray to the operator and on his clothing.
While conventional open air flow systems have been built with at least some portions being mobile such as the filter unit to accomodate changing the color being sprayed, there have been no recirculating air systems and hence no completely mobile recirculating systems in which the powder spray booth, the fan, filter and all connecting ducts are self-contained on a mobile platform for alignment with an overhead article conveyor.